|United States Patent||4,912,721|
|Pidgeon, Jr. , et al.||March 27, 1990|
Apparatus for transmitting data spread across at least a portion of the bandwidth of a cable television channel comprises a carrier signal oscillator, a frequency divider, a pseudorandom sequence generator and two exclusive OR gates. A first exclusive OR gate serves to spread a data signal across the pseudorandom noise sequence generator having a much higher chip rate than the bit rate of the data signal. The second exclusive OR gate modulates the spread spectrum data signal to a carrier frequency for transmission over the cable television channel. The apparatus may be applied for return path transmission in the 0-30 megahertz band which is high susceptible to interference noise and provides approximately a 20 dB signal to interference ratio advantage over known data coding and transmission schemes. A microprocessor normally present in a cable television terminal may format data for transmission, control the spread spectrum modulation process and control gain control circuitry for introducing an appropriate power level into the cable plant.
|Inventors:||Pidgeon, Jr.; Rezin E. (Atlanta, GA), Zendt; Frederick T. (Norcross, GA), Thompson; Leo J. (Lilburn, GA)|
|Filed:||April 29, 1988|
|Current U.S. Class:||375/149 ; 348/E7.07; 375/145; 375/E1.017; 380/1|
|Current International Class:||H04B 1/707 (20060101); H04N 7/173 (20060101); H04K 001/00 ()|
|Field of Search:||375/1 380/34,12 455/5|
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|4635274||January 1987||Kubora et al.|
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"Spread Spectrum Used in Distributed Home Bus" by Richard Dohetry News Release of NEC Showing Approximately Jan. 1988..